How do you overlay an image on a shader in Cycles?
Take the Alpha socket from your image, and plug it in to the Fac of the Mix Shader node. Then switch the Diffuse BSDF to the bottom socket of the Mix Shader, and the Anisotropic BSDF to the top shader socket.

The black and white alpha channel will control which parts of the material get which node. A value of 0 goes to the bottom socket and a value of 1 goes to the top socket.